Retire runtime/API/UI monitored-system volume enforcement now that infrastructure monitoring is no longer capped.
Keep only legacy metadata scrubbing and purchase-start compatibility for old max_monitored_systems references.
Rename the remaining preview surface to monitored-system impact and make previews explanatory rather than save-blocking.
Update subsystem contracts and RA7 evidence for the caps-retired invariant.
The free-tier onboarding overflow adds +1 to MaxMonitoredSystems for 14
days after initial setup. Once rc.2 made self-hosted core monitoring
uncapped (MaxMonitoredSystems = 0 on Free), the bonus math silently
converted "unlimited" into a hard cap of 1 — the UI then surfaced
"Over plan by N. N monitored, 1 included." on healthy installs.
Guard the addition on limit > 0 at all three call sites (ledger path,
commercial entitlement payload, runtime capabilities payload) so the
bonus only extends plans that actually have a cap.
Refs #1429
rcourtman